The present invention relates to a motor vehicle gearbox and more specifically to the arrangement of the gear selector forks on the respective stationary rods.
Japanese Patent Application JP59108125 discloses a gear selector fork supported on a sliding rod with the arrangement of a pair of double-diameter bushes in between. A helical spring is axially arranged between the two bushes and exerts on them a resilient force tending to move them away from each other. The two bushes are constrained in an axially outward direction by respective snap rings mounted on the rod. Actuation of the selector fork by the sliding rod therefore produces a relative displacement, dampened by the helical spring, between the two components.
Unpublished European Patent Application 06425825.4 in the name of the Applicant discloses a motor vehicle gearbox comprising a case, a stationary rod supported by the case, a pair of gear selector forks mounted slidably on the rod and end-of-travel members arranged on the rod so as to define the end-of-travel positions of the gear selector forks, the end-of-travel members comprising a pair of bushes which are separate from the rod and each have a first axially external portion with a larger diameter and a second axially internal portion with a smaller diameter so as to define at least one axial abutment surface for the adjacent gear selector fork.
European Patent Application EP 1 832 786 in the name of the Applicant also discloses a gear selector fork for a motor vehicle gearbox comprising a body designed to support the fork slidably along a stationary rod of the gearbox, a pair of prongs projecting from the body and forming at their distal ends respective actuating portions able to operate a coupling sleeve of the gearbox, and an actuating nose fixed to the body so as to impart to the fork the sliding movement along the rod. The body, the prongs and the actuating nose are formed by sheet-metal parts obtained by means of blanking and bending and fixed to each other by means of welding. The body of the fork includes a central plate and a pair of support plates which extend at right angles from the opposite ends of the central plate and have respective coaxial through-holes able to guide the fork along the rod. Both the through-holes in the fork support plates are provided with respective plastic bushes having the function of reducing friction and wear. The bushes are advantageously obtained by means of plastic overmoulding so as to avoid the need to perform additional machining of the fork.